1. Field of the Invention
The invention pertains to a bellows for hydraulic, hydropneumatic, or pneumatic piston-cylinder units, especially for vibration dampers or MacPherson strut units for motor vehicles, wherein the bellows is located between the end of the piston rod and the cylinder and covers the part of the piston rod which projects out from the cylinder to provide protection against dirt and/or damage. The interior space of the bellows undergoes a change in volume as a result of the relative movement of the parts with respect to each other and at least one flow connection leading to the interior of the bellows is provided to allow an incoming and/or outgoing flow of air.
2. Description of the Related Art
Bellows for piston-cylinder units are already known, for example, from German Patent Document DE 102 00 608 A1. In these cases, a vibration damper or a MacPherson strut unit is provided with a bellows for protection against dirt and/or damage. As a result of the relative movement between the piston rod and the cylinder, the interior of the bellows undergoes a change in volume, for which purpose an opening leading to the interior of the bellows is provided to allow air to enter and leave. Because the vibration dampers or MacPherson strut units are exposed in the wheel well of the vehicle to water spray and dirt, the use of a bellows can protect the piston rod, but, according to the state of the art, the disadvantage is that incoming air also arrives from this wheel well, and the outgoing air terminates in it.